A growing need exists for data on the enzymatic bioactivation and detoxification of potential toxic compounds in humans. This proposal is focused towards using purified preparations of human cytochrome P-450, NADPH-cytochrome P-450 reductase, and epoxide hydrolase to answer questions about the reactions catalyzed by these enzymes and the incidence of various forms of these enzymes in human populations. Specifically, this application proposes to: (1) obtain additional preparations of the above three enzymes from human liver, purified to apparent homogeneity and including variants of these enzymes, (2) compare some of the physical, chemical, and immunological properties to the corresponding enzymes isolated from rats and rabbits, (3) examine the abilities of individual human cytochromes P-450 to activate procarcinogens to metabolites irreversibly bound to DNA and protein, (4) examine these activities in surgical biopsies, (5) examine the metabolic profiles of benzo(a)pyrene and other carcinogens and substrates and elucide the role of epoxide hydrolase in human systems, (6) compare the enzymes in different humans using sodium dodecyl sulfate polyacrylamide electrophoresis coupled with peroxidase-antiperoxidase visualization of anitbody binding, (7) use the above technique in conjunction with peptide mapping to identify common antigenic sites of human enzymes, (8) develop monoclonal antibodies to individual forms of the human enzymes, (9) to develop competitive radioimmune or enzyme-linked immune assays for individual forms of these human enzymes, and (10) to localize the above enzymes in human tissues using immunohistochemical techniques.